In a four speed gearbox, the operating lever by means of which the desired gear ratio or “speed” is selected, is guided to move in an “H” shape. The uprights of the “H” define gear selection channels and the horizontal path between the two gear selection channels defines the neutral position of the gearbox, i.e. the setting in which the input shaft is totally disengaged from the output shaft. By first sliding the operating lever into the left gear selection channel and then moving it to the “up” position, the first speed is selected. If the operating lever is kept in the left gear selection channel but moved from the “up” position, through the neutral position, to the “down” position, the second speed is selected. To select the third speed, while in neutral the operating lever is first moved to the right gear selection channel and then “up”. Finally, downward movement of the operating lever while in the second gear selection channel will engage the fourth speed.
Typically, the gear stick is supported between two selectors, often referred to as selector forks on account of their shape. Each of the selectors slides a dog along a shaft to couple gears for rotation with the shaft. One of the selectors selects first and second speed while the other selector selects third and fourth speed. As the gear stick is pivoted from side to side while the gearbox is in neutral, it engages with one or other of the two selectors.
Joysticks are known for remotely controlling change speed gearboxes in a vehicle. In known designs, the operating lever on the joystick is connected to the gear stick of the gearbox by means of two Bowden cables. One of the cables ensures that the gear stick is moved horizontally to engage the appropriate selector as the operating lever on the joystick is moved from side to side and the other moves the gear stick up and down to select the desired speed as the operating lever of the joystick is moved up and down.
A major drawback of known joysticks is the lack of “feel” in the operating lever. It is desirable for the operating lever to require short crisp movements in an H shape and for it to offer resistance to side to side movement once a speed has been selected while permitting free side to side movement when the gearbox is in neutral. Such precise control is not achieved with known designs, which have also suffered from being bulky and of complicated construction.